Rebecca A. Gardner

Current concepts in the diagnosis and management of cytokine release syndrome

As immune-based therapies for cancer become potent, more effective, and more widely available, optimal management of their unique toxicities becomes increasingly important. Cytokine release syndrome (CRS) is a potentially life-threatening toxicity that has been observed following administration of natural and bispecific antibodies and, more recently, following adoptive T-cell therapies for cancer. CRS is associated with elevated circulating levels of several cytokines including interleukin (IL)-6 and interferon γ, and uncontrolled studies demonstrate that immunosuppression using tocilizumab, an anti-IL-6 receptor antibody, with or without corticosteroids, can reverse the syndrome. However, because early and aggressive immunosuppression could limit the efficacy of the immunotherapy, current approaches seek to limit administration of immunosuppressive therapy to patients at risk for life-threatening consequences of the syndrome. This report presents a novel system to grade the severity of CRS in individual patients and a treatment algorithm for management of CRS based on severity. The goal of our approach is to maximize the chance for therapeutic benefit from the immunotherapy while minimizing the risk for life threatening complications of CRS.

Intent to treat leukemia remission by CD19CAR T cells of defined formulation and dose in children and young adults

Transitioning CD19-directed chimeric antigen receptor (CAR) T cells from early-phase trials in relapsed patients to a viable therapeutic approach with predictable efficacy and low toxicity for broad application among patients with high unmet need is currently complicated by product heterogeneity resulting from transduction of undefined T-cell mixtures, variability of transgene expression, and terminal differentiation of cells at the end of culture. A phase 1 trial of 45 children and young adults with relapsed or refractory B-lineage acute lymphoblastic leukemia was conducted using a CD19 CAR product of defined CD4/CD8 composition, uniform CAR expression, and limited effector differentiation. Products meeting all defined specifications occurred in 93% of enrolled patients. The maximum tolerated dose was 106 CAR T cells per kg, and there were no deaths or instances of cerebral edema attributable to product toxicity. The overall intent-to-treat minimal residual disease-negative (MRD-) remission rate for this phase 1 study was 89%. The MRD- remission rate was 93% in patients who received a CAR T-cell product and 100% in the subset of patients who received fludarabine and cyclophosphamide lymphodepletion. Twenty-three percent of patients developed reversible severe cytokine release syndrome and/or reversible severe neurotoxicity. These data demonstrate that manufacturing a defined-composition CD19 CAR T cell identifies an optimal cell dose with highly potent antitumor activity and a tolerable adverse effect profile in a cohort of patients with an otherwise poor prognosis. This trial was registered at www.clinicaltrials.gov as #NCT02028455.

CD19 CAR immune pressure induces B-precursor acute lymphoblastic leukaemia lineage switch exposing inherent leukaemic plasticity

Adoptive immunotherapy using chimeric antigen receptor (CAR) expressing T cells targeting the CD19 B lineage receptor has demonstrated marked success in relapsed pre-B-cell acute lymphoblastic leukaemia (ALL). Persisting CAR-T cells generate sustained pressure against CD19 that may drive unique mechanisms of resistance. Pre-B ALL originates from a committed pre-B cell or an earlier progenitor, with potential to reprogram into other hematopoietic lineages. Here we report changes in lineage markers including myeloid conversion in patients following CD19 CAR therapy. Using murine ALL models we study the long-term effects of CD19 CAR-T cells and demonstrate partial or complete lineage switch as a consistent mechanism of CAR resistance depending on the underlying genetic oncogenic driver. Deletion of Pax5 or Ebf1 recapitulates lineage reprogramming occurring during CD19 CAR pressure. Our findings establish lineage switch as a mechanism of CAR resistance exposing inherent plasticity in genetic subtypes of pre-B-cell ALL.

CD19-redirected chimeric antigen receptor-modified T cells: a promising immunotherapy for children and adults with B-cell acute lymphoblastic leukemia (ALL):

Relapsed and chemotherapy-refractory B-cell acute lymphoblastic leukemia (B-ALL) remain significant causes of cancer-associated morbidity and mortality for children and adults. Development of new molecularly targeted treatment strategies for patients with high-risk B-ALL is thus a major preclinical and clinical priority. Adoptive cellular therapy with patient-derived human T cells genetically engineered to express CD19 redirected chimeric antigen receptors (CD19 CAR T cells) is one immunotherapeutic modality that has recently demonstrated remarkable efficacy in re-inducing remission in patients with multiply relapsed B-ALL. Investigative teams at several major cancer centers are currently conducting phase I clinical trials in children and/or adults with relapsed/refractory B-ALL to assess the safety and to identify the maximally tolerated dose of each group’s CD19 CAR T-cell product. All groups have reported major clinical toxicities associated with CD19 CAR T-cell treatment, including cytokine release syndrome (CRS) and macrophage activation syndrome, neurologic dysfunction and aplasia of normal B lymphocytes, while CD19 CAR T cells persist in vivo. Toxicities have generally been transient or manageable with supportive care measures. Some patients with life-threatening CD19 CAR T-cell induced sequelae have received anti-cytokine receptor antibody treatment to diminish CRS symptoms and/or corticosteroids to terminate CAR T-cell proliferation. Remarkably, 67–90% of children and adults with B-ALL treated with CD19 CAR T cells in these trials have achieved morphologic leukemia remission with many patients also in molecular remission. The duration of CD19 CAR T cell persistence in vivo has varied appreciably among treated patients and likely reflects differences in the CD19 CAR constructs utilized at each institution. CD19-positive and CD19-negative B-ALL relapses after CD19 CAR T-cell treatment have occurred in some patients. Phase II trials to assess the efficacy of CD19 CAR T-cell immunotherapy in larger cohorts of patients with relapsed/refractory B-ALL are ongoing or planned.

Outcomes of adults and children with primary mediastinal B-cell lymphoma treated with dose-adjusted EPOCH-R

Treatment with dose‐adjusted EPOCH (etoposide, doxorubicin, cyclophosphamide, vincristine, prednisone) chemotherapy and rituximab (DA‐EPOCH‐R) has become the standard of care for primary mediastinal B‐cell lymphoma (PMBCL) at many institutions despite limited data in the multi‐centre setting. We report a large, multi‐centre retrospective analysis of children and adults with PMBCL treated with DA‐EPOCH‐R to characterize outcomes and evaluate prognostic factors. We assessed 156 patients with PMBCL treated with DA‐EPOCH‐R across 24 academic centres, including 38 children and 118 adults. All patients received at least one cycle of DA‐EPOCH‐R. Radiation therapy was administered in 14·9% of patients. With median follow‐up of 22·6 months, the estimated 3‐year event‐free survival (EFS) was 85·9% [95% confidence interval (CI) 80·3–91·5] and overall survival was 95·4% (95% CI 91·8–99·0). Outcomes were not statistically different between paediatric and adult patients. Thrombotic complications were reported in 28·2% of patients and were more common in paediatric patients (45·9% vs. 22·9%, P = 0·011). Seventy‐five per cent of patients had a negative fluorodeoxyglucose positron emission tomography (FDG‐PET) scan at the completion of DA‐EPOCH‐R, defined as Deauville score 1–3. Negative FDG‐PET at end‐of‐therapy was associated with improved EFS (95·4% vs. 54·9%, P < 0·001). Our data support the use of DA‐EPOCH‐R for the treatment of PMBCL in children and adults. Patients with a positive end‐of‐therapy FDG‐PET scan have an inferior outcome.

Treatment-related adverse events associated with a modified UK ALLR3 induction chemotherapy backbone for childhood relapsed/refractory acute lymphoblastic leukemia.

The UK ALLR3 (R3) regimen has been adopted to treat pediatric relapsed acute lymphoblastic leukemia (ALL) by many centers in the United States and has become a preferred therapeutic backbone for testing novel agents in clinical trials. A detailed toxicity profile of this platform has not previously been reported. The toxicity and response rates for its use beyond first relapse are unknown.

Outcome of children with multiply relapsed B-cell acute lymphoblastic leukemia: a therapeutic advances in childhood leukemia & lymphoma study

The survival of pediatric patients with multiply relapsed and/or refractory (R/R) B-cell acute lymphoblastic leukemia has historically been very poor; however, data are limited in the current era. We conducted a retrospective study to determine the outcome of multiply R/R childhood B-ALL treated at 24 TACL institutions between 2005 and 2013. Patient information, treatment, and response were collected. Prognostic factors influencing the complete remission (CR) rate and event-free survival (EFS) were analyzed. The analytic set included 578 salvage treatment attempts among 325 patients. CR rates (mean ± SE) were 51 ± 4% for patients with bone marrow R/R B-ALL who underwent a second salvage attempt, 37 ± 6% for a third attempt, and 31 ± 6% for the fourth through eighth attempts combined. For patients achieving a CR after their second, third, and fourth through eighth attempts, the 2 year EFS was 41 ± 6%, 13 ± 7%, and 27 ± 13% respectively. Our results showed slight improvement when compared to previous studies. This is the largest and most recent study to date that evaluates the outcome of this patient population. Our data will provide detailed reference for the evaluation of new agents being developed for childhood B-ALL.

CD19CAR T cells: From humble beginnings to cancer immunotherapy's poster child.

AbstractThe conceptual foundation and technical evolution of T-cell genetic engineering for the purpose of retargeting antigen specificity as a clinical immunotherapy modality in oncology have been decades in the making, with many laboratories providing important contributions to overall progress. The development of the component parts of this technology has required the amalgamation of divergent scientific disciplines including cellular immunology, lymphocyte signaling biology, molecular biology, vector virology, and practical improvements in T-cell culture systems. Together with advances in the understanding of clinical variables that facilitate persistent engraftment and expansion of adoptively transferred T cells, the field of CD19CAR research evolved as a logical venue for revealing proof-of-principle clinical antitumor activity. Indeed, the modality has definitively crossed the threshold from a preclinical model system to a therapeutic approach with demonstrable potent antileukemic efficacy in patients harboring advanced and refractory leukemias. The dramatic responses seen in CD19CAR T-cell clinical trials from multiple institutions does not signal an end to the evolution of CD19CAR T cells, as along with early clinical successes, new challenges have emerged that require further refinement of this nascent therapeutic platform.

Substitution with doxorubicin for daunorubicin during induction for high risk pediatric acute lymphoblastic leukemia results in increased toxicity

To the Editor: Widespread drug shortages have affected the availability of chemotherapy agents commonly used to treat pediatric ALL [1]. Induction chemotherapy for high risk acute lymphoblastic leukemia (HR ALL) consists of vincristine, PEGaspargase, daunorubicin, and a glucocorticoid with associated low rates of morbidity and mortality, and a high rate of remission efficacy [2]. The shortage of daunorubicin, which began in the spring of 2011, compromised the delivery of standard induction chemotherapy to pediatric HR-ALL patients. Daunorubicin and doxorubicin are historically considered dose equivalent in the treatment of ALL based upon in vitro testing showing similar sensitivity in untreated pediatric ALL samples [3]. Two clinical studies in acute myelogenous leukemia (AML) comparing the two anthracyclines suggested that daunorubicin has a lower toxicity profile than doxorubicin [4,5]. During the time of daunorubicin shortage, our institution used doxorubicin at a 1:1 substitution. To examine the differences in toxicity and efficacy between doxorubicin and daunorubicin during induction therapy for HR ALL, we conducted a retrospective case control study. We performed a retrospective chart review of all HR ALL patients who received induction therapy at Seattle Children’s Hospital from January 01, 2009 until July 31, 2011. During the study period 45 patients met eligibility criteria, nine treated with doxorubicin and 37 with daunorubicin. The two groups had similar clinical characteristics; including age, initial white blood cell count, gender, and pre-B or T cell disease (Table I). The patients who received doxorubicin were more likely to have missed or delayed doses of doxorubicin/daunorubicin (22% vs. 5%) or vincristine (22% vs. 0%). CNS directed therapy was not affected by the doxorubicin substitution. Although all of the patients in the doxorubicin treated group had an M1 marrow (<5% residual lymphoblasts by morphology) by Day 15, 44.4% were Day 29 minimal residual disease positive ( 0.01% disease) versus 27% in the daunorubicin treated group (P 1⁄4 0.188). Toxicity was increased in the doxorubicin treated group of patients, with increased rates of mucositis (33.3% vs. 10.8%) and typhilitis (22.2% vs. 0%; Table I). One patient with typhlitis died with disseminated fungal (Zygomycetes) infection at Day 19 of induction therapy. Overall, microbiologically documented fungal infections were more common in the doxorubicin treated group (33.3% vs. 5.4%), although the frequency of bacteremia was similar. Our data suggest that a 1:1 substitution of doxorubicin for daunorubicin will not result in equivalent toxicity and that doxorubicin increases the rates of mucositis and typhlitis when used in a similar induction regimen. However, the appropriate dose conversion is not clear. The small size of our doxorubicin-treated population prevents a firm conclusion about the impact on remission induction, including end-induction minimal residual leukemia levels. Doxorubicin substitution during induction was associated with chemotherapy omissions, likely related to the increased toxicity associated with doxorubicin in this induction regimen. Several cooperative groups and institutions routinely administer doxorubicin during induction for HR ALL but on a different schedule [6–8]. In the event of future daunorubicin shortage, alternative induction options could be considered, including induction regimens with two consecutive daily doses of doxorubicin rather than weekly dosing [6].

Lymphocyte apheresis for chimeric antigen receptor T-cell manufacturing in children and young adults with leukemia and neuroblastoma: APHERESIS FOR CAR T-CELL MANUFACTURING

The first step in the production of chimeric antigen receptor T cells is the collection of autologous T cells using apheresis technology. The procedure is technically challenging, because patients often have low leukocyte counts and are heavily pretreated with multiple lines of chemotherapy, marrow transplantation, and/or radiotherapy. Here, we report our experience of collecting T lymphocytes for chimeric antigen receptor T‐cell manufacturing in pediatric and young adult patients with leukemia, non‐Hodgkin lymphoma, or neuroblastoma.